Fixed failing TestCase for iso-8859 encoded files with Umlauts.

lib/simplecov/source_file.rb

@@ -30,6 +30,7 @@ def initialize(src, line_number, coverage)
         raise ArgumentError, "Only Fixnum and nil accepted for coverage" unless coverage.kind_of?(Fixnum) or coverage.nil?
         @src, @line_number, @coverage = src, line_number, coverage
         @skipped = false
+        @src.encode!('UTF-8', 'UTF-8', :invalid => :replace) if @src.respond_to?(:encode!)
       end
 
       # Returns true if this is a line that should have been covered, but was not
@@ -172,3 +173,4 @@ def round_float(float, places)
     end
   end
 end
+